Can a rash turn HIV test results false negative?

This Premium Q&A, reviewed and published, features a real conversation between an iCliniq user and a physician.

Patient's Query

Hello doctor,

I have a rash (quite extensive, but mainly on my arms and legs) that has been present for the last five days. I had an HIV test, 1,2Ab, and p24 done yesterday, which has come back negative (test done nine days after last unprotected oral sex). Is there still a risk that this could be a false negative even though the rash has been present for at least four days before testing? I do not have any other signs or symptoms.

Does a rash suggest seroconversion (if truly infected), and therefore would this mean that the AB and AG tests should test positive a few days after the onset of the rash?

Please help.

Answered by Dr. Ravinder K. Sachdeva

Hello,

Welcome to icliniq.com

I understand your concern.

The onset of rash could be a coincidental finding and does not signify seroconversion or acute retroviral syndrome manifestation. It could have various reasons. I would like to see a picture of the rash (if comfortable) to make a clinical impression. I just want to let you know that having a negative test result after nine days of exposure is likely to give your baseline HIV (Human Immunodeficiency Virus) status (pre-existing, before exposure).

Unprotected oral sex carries a negligible to very low risk of HIV acquisition, especially if there are bleeding gums, active oral ulcers, or infection. Recommendations are to get the first HIV antibody test at four to six weeks of exposure, and if negative, get a confirmation HIV antibody test at three months of last exposure. After 11 to 14 days of exposure, you can get HIV RNA PCR (polymerase chain reaction) (qualitative). But confirmatory tests are antibody-based tests.

Kindly follow up if you have more concerns.

I hope this helps.

Patient's Query

Hello doctor,

I take the RCR PCR test on day 16. The rash has now increased. It started on my inner elbows and then was on my thighs, behind my armpit, and on my thighs. It is not on my chest. It is also on my hands and some spots on my palms. The rash is also itchy. Starts raised and then becomes flatter with redness behind.

Is this still accurate?
How likely is it to get an acute HIV rash around six days after exposure?
Does this also make it unlikely?

Kindly suggest.

Answered by Dr. Ravinder K. Sachdeva

Hello,

Welcome back to icliniq.com

I understand your concern.

A negative HIV RNA PCR (polymerase chain reaction) at 16 days would be quite reassuring. But still antibody tests, as I have suggested, would still be required. Unlikely to have an acute rash at around six days. This picture of the rash is not specific to HIV. Need to keep the area dry. Apply the absorbing powder and take the tablet Levisiz (Levocetirizine) 10 mg if itching is present. Get a dermatology opinion on it.

I hope this helps.

Thank you.

Patient's Query

Hello doctor,

I have attached a picture of where the rash started on my inner elbow. This is what it looks like today. I will get a dermatology opinion. Also, it is improving with steroid cream.

Is this also not specific to HIV?

Thank you for your advice.

Answered by Dr. Ravinder K. Sachdeva

Hello,

Welcome back to icliniq.com

I understand your concern.

I have reviewed the pictures (attachment removed to protect the patient's identity). Have you taken any medicine during this period?

Kindly follow up if you have more concerns.

Regards.

Thank you.

Patient's Query

Hello doctor,

Yes. Oral prednisone five-day course and some antihistamine. Also, Flucloxacillin.

Is this rash typical for HIV?

Kindly suggest.

Answered by Dr. Ravinder K. Sachdeva

Hello,

Welcome back to icliniq.com

I understand your concern.

Does this rash appear after taking Flucloxacillin? And, this is not typical for HIV.

I hope this helps.

Kindly follow up if you have more concerns.

Thank you.

Patient's Query

Hello doctor,

No, it appeared well before Flucloxacillin.

How sensitive is the PCR test at detecting the infection at 15 days? Is it more than 95 percent?
My rash is improving well with a stronger steroid cream (Eumovate).
Is this something you would expect for HIV?

Kindly suggest.